They make an external battery case that holds 6 D-cell batteries, this lasts my kids days of intermittent play. Radio Shack carries multiple cell battery holders that hold D's and they also carry connectors for the power supply. We use Renewal batteries in whichever configuration (don't let them discharge completely). You should be able to use a 9V (1.5V * 6) supply with a 500ma rating (1 amp would be better) mainly for peak current capability. Typical AA batteries are about 600mAh (milliamp-hours). Divide 600 by 3 hours (conservative) and you get 200mA current drain. So 500ma would take care of it. I just found the kid's dual car adapter and it is rated at 10.5 volts with 800ma. Just be very careful that the center of the pin is + and the outer is - (you can destroy the Lynx with wrong connections). Good luck.
RE: Lynx Power Supply - Voltage & mA rating ? 
